WO2004/082383 discloses use of triazolopyrimidine derivatives having a specific chemical structure as a nematicide. However, these compounds are different from the compounds of the present invention in the chemical structure. Further, WO2002/02563 discloses a method of preventing or treating growth of cancerous tumor cells and associated diseases, which comprises applying an effective amount of a triazolopyrimidine derivative to a mammal. However, it failed to disclose the compounds of the present invention and use of the compounds of the present invention as a pesticide.